Any solution for this tax avoidance would have to be international imo. Even if all the crown dependencies and overseas territories stopped being tax havens, these companies and individuals would just run some similar scheme in Monaco, Mauritius or some other place.
The whole tax code is too complex imo. If it started from the premise that every individual, company, trust or other institution pays X per cent of any money they receive, and then have a set of exemptions (eg, first £12k of earned income, interest from an ISA, pension contributions up to the current limit).
Then, the onus would would be on the taxpayer to demonstrate that the money was in one of the exempt categories, rather than on HMRC having to prove that it was taxable under the huge web of tax legislation that currently exists.
My BIL has made £1.5 m plus in the last 5 years and not paid a penny in tax. He simply "moves into" the properties he develops so that they count as his home. The term is used loosely, in practice he just pays council tax, utility bills and his post sent there. If it's a really big, prestigious renovation, the family will move in for a few months once it's finished and on the market.
It's obvious to anyone that this is their sole source of income, neither of them do any other work or have other investments. And he has the audacity to complain about public services, especially the 9 months he had to wait for NHS surgery.